Current guest/host/halt stats don't show when we are currently halting
well. If a guest halts for a long period of time they could appear
pathologically blocked but really it's the opposite there's nothing to
do.
Simply count the number of times we enter and leave the kvm_vcpu_block
function per vcpu, if they are unequal, then a VCPU is currently
halting.
The existing stats like halt_exits and halt_wakeups don't quite capture
this. The time spend halted and halt polling is reported eventually, but
not until we wakeup and resume. If a guest were to indefinitely halt one
of it's CPUs we would never know, it may simply appear blocked.
Original-by: Cannon Matthews <cannonmatthews@xxxxxxxxxx>
Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
---
include/linux/kvm_host.h | 4 +++-
include/linux/kvm_types.h | 2 ++
virt/kvm/kvm_main.c | 2 ++
3 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d447b21cdd73..23d2e19af3ce 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1459,7 +1459,9 @@ struct _kvm_stats_desc {
STATS_DESC_LOGHIST_TIME_NSEC(VCPU_GENERIC, halt_poll_fail_hist, \
HALT_POLL_HIST_COUNT), \
STATS_DESC_LOGHIST_TIME_NSEC(VCPU_GENERIC, halt_wait_hist, \
- HALT_POLL_HIST_COUNT)
+ HALT_POLL_HIST_COUNT), \
+ STATS_DESC_COUNTER(VCPU_GENERIC, halt_block_starts), \
+ STATS_DESC_COUNTER(VCPU_GENERIC, halt_block_ends)
extern struct dentry *kvm_debugfs_dir;
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index de7fb5f364d8..ea7d26017fa6 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -93,6 +93,8 @@ struct kvm_vcpu_stat_generic {
u64 halt_poll_success_hist[HALT_POLL_HIST_COUNT];
u64 halt_poll_fail_hist[HALT_POLL_HIST_COUNT];
u64 halt_wait_hist[HALT_POLL_HIST_COUNT];
+ u64 halt_block_starts;
+ u64 halt_block_ends;
};
#define KVM_STATS_NAME_SIZE 48
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3e67c93ca403..5c3a21d2fbea 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3206,6 +3206,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
bool waited = false;
u64 block_ns;
+ ++vcpu->stat.generic.halt_block_starts;
kvm_arch_vcpu_blocking(vcpu);
start = cur = poll_end = ktime_get();
@@ -3285,6 +3286,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
trace_kvm_vcpu_wakeup(block_ns, waited, vcpu_valid_wakeup(vcpu));
kvm_arch_vcpu_block_finish(vcpu);
+ ++vcpu->stat.generic.halt_block_ends;
}
EXPORT_SYMBOL_GPL(kvm_vcpu_block);
base-commit: a3e0b8bd99ab098514bde2434301fa6fde040da2
--
2.33.0.rc1.237.g0d66db33f3-goog
